Spatio-temporal distribution of microplastics in surface water of typical urban rivers in North China, risk assessment and influencing factors

Abstract

Urban rivers serve as primary receivers and transporters of microplastics. In this study, the spatio-temporal distribution of microplastics in the surface waters of the Zhang River and Fuyang River, which are representative urban rivers in North China, was investigated. The risk evaluation and influencing factors were also analyzed. The results indicated that the average abundance of microplastics in the surface waters of the Zhang River was higher during the dry season, while the average abundance in the Fuyang River was lower than that observed in the Zhang River during the wet season. Furthermore, the abundance of microplastics exhibited an increasing trend from upstream to downstream. The predominant polymer types of microplastics identified are polyethylene (PE) and polypropylene (PP), with the majority being blue fibers 0–2 mm in size. In comparison to the Zhang River, the Fuyang River exhibits a higher diversity index of microplastics, with more varied and complex sources attributed to anthropogenic activities. The risk of microplastic pollution in the Zhang and Fuyang rivers was found to increase downstream. The spatial distribution of microplastics is influenced by both natural conditions and anthropogenic activities, with upstream areas dominated by natural factors and downstream areas dominated by human activities. This study provides a reference for understanding microplastic pollution levels and sources in urban rivers of Northern China.